Modified 8v project head

Discussion in '8-valve' started by mr hillclimber, Nov 5, 2007.

  1. Jon Olds Forum Junkie

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    Similar experience 10 + years ago, my first KR race project. Took a hacksaw to a new Ashley 4 to 1 collector box to port the inside. (ie get rid of the rough and ready excess mild steel) Then welded it back up....
     
  2. quattro64 Forum Member

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    Are you sure it is a DX head? I thought the DX heads were solid lifter and had only one alternator mounting bracket cast on to the head.
     
  3. chopperoli Forum Member

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    This is as good a place as any to show you my 1.6 Heron (Mk1 GTI, EG) head with 40/35 valves and some nice port work. For my Mk1 Scirocco :)
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  4. pre67 Forum Member

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    hi there loveing the thread top work might i just add that porting is RELLY BOREING as i have found out this week might be because i have been polishing 12 wheels for weeks[xx(]


    but yer my qustion is why is it not a good idear to grind the floor of the port ? as i have ground about 1 or 2mm off mine is this bad ?


    loz
     
    Last edited by a moderator: Mar 1, 2010
  5. mr hillclimber Club GTI Supporter and Sponsor

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    Thanks...

    It's because you need to keep the short side turn as smooth as possible... if you remove material (or too much... sometimes you have to depending on the application) from the port floor the air will have a sharper turn to make when it goes around the short side.

    It can be tedious, especially after you've done the first one then realise there's 7 more ports to do!
     
  6. pre67 Forum Member

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    ok i just thought i might hit a water/oil or someing. going to do some more 2day i will post some pics to show how im geting on and also i have had some cool injector plugs made
     
  7. mr hillclimber Club GTI Supporter and Sponsor

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    Good man... keep at it.
     
  8. pre67 Forum Member

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    another quick qustion what do you use to get the finel finsh i have been useing small flap wheels but they dont larst long and it takes ages


    cheers

    loz
     
  9. bazmcav New Member

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    did you ever get any figures off the 2.0 8v head build? [:D]
    quality thread:clap:
     
  10. mr hillclimber Club GTI Supporter and Sponsor

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    I guess you mean power figures?

    Nope not yet. My man has recently fitted a 4-1 manifold from tsr which has given it a bit more pull and smoothed out the rumpa rumpa idle a bit. Now I have easy access to a rolling road again we'll get it on soon and check/adjust the fueling and swing the vernier, though it's plenty quick enough as it is, the standard (new) clutch is "just" holding on.

    The head should flow in the region of other std valve 8v's I've done more recently, so around 88-90cfm on the inlet and 55-57cfm on the exhaust.

    I'll get some power figures up as soon as we do some.
     
  11. Tristan Forum Junkie

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    Is that the same mani as the TSR mk2 GTi one that's "off the shelf"?
     
  12. tones61

    tones61 Forum Member

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    hi mate,yes its their miltek 4 into 1 stainless manifold,they dont make one for the 2e tall block in a mk2 ,so had to space up front mount(about an inch) to tilt engine back and dress back bukhead a bit with a hammer and big crowbar,hope this helps,:thumbup:
     
  13. Tristan Forum Junkie

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    I've one going on to a mildly modded 1.8 Mk2 , so glad to hear it actually works!
     
  14. R.b!n_16v Forum Member

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    With head is the best to start with, i got now a gti with the engine code pf and runs on digifant 2.

    Im going to port it just like how you did it(try) hihi, which cam will suit the best i was thinking of this one: 279/279 degrees .Max. valvelift 11.50/11.50mm. Lift in BDP 2.70 / 2.70mm(or a 282). They had also some high flow valves maybe i will use some of these. Now i need a donor head which one will i use just a normal gti head from a 1800cc?
     
  15. mr hillclimber Club GTI Supporter and Sponsor

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    Base it on the current head, or a spare one of the same type. The std valves do a great job when re-profiled.

    Sounds like a decent cam, it'll give good road performance.
     
  16. R.b!n_16v Forum Member

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    hi,

    going to start with the porting this weekend now one question, make the inlet shape round like te valve or give it the oval shape that it allready has?

    greetz
     
  17. mr hillclimber Club GTI Supporter and Sponsor

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    Round... tell me the inlet valve size and I'll tell you port size needed and the easy way to achieve it.
     
  18. R.b!n_16v Forum Member

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    pf head with 40mm inlet i thought 33-34 mm exhaust. I'd read that is was 85% of the valve seat and that was about 33mm right? Maybe im going to skim the head, how much should i skim to go from 10:1 to 11,5:1 or 11:1cr
     
  19. R.b!n_16v Forum Member

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    I started poorting now this weekend. Its a hard job i have 3 inlet ports done! now one to go en the exhaust ports. Some tips to get it realy smooth i have a lot of bumps. Grind them away? hard job i think, its al about practice to(my first time)
     
  20. mr hillclimber Club GTI Supporter and Sponsor

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    Open the inlet ports to 31mm, the venturi below the valve seat to 34mm, taper the port walls down from below the venturi to the roof.

    Have an old valve turned down to 30mm, rough out the ports so the valve fits down them... most of the material will need to come from the sides of the ports, a little from the roof, "none" from the floor.

    Use a 60 grit flap wheel to smooth over the rough ground ports. If you havnt been too agressive with the roughing out stage it wont take much to smooth over... this opperation will take out the last 1mm to make the port 31mm.

    The key is the throat/valve seat area... opening the ports without the seat work wont achieve much, apart from boredum with poting heads!

    Yep, not as easy as it looks!

    Once you've done the above be very carefull with the short side (floor) turn... follow the guide here for this... or shout up here.

    If you hav'nt already, have the valve guides removed by a machine shop... I wouldnt recommend doing it youself for the 1st time.

    With the 33mm exhaust valve... open the throat to 28mm, then taper out to 31mm into the main port.

    C.R will totally depend on the cam you plan to use.
     

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